Antibodies, lymphocytes and diversity Flashcards
Describe the receptor on the surface of T-cells
Heterodimer with alpha and beta chains + one binding site unique to the cell.
Describe the receptor on the surface of B-cells
Made up of 2 identical heavy and 2 identical light chains with 2 antigen binding sites per cell.
What are the segments that make up the variable region of the heavy chain binding site on the surface of a lymphocyte?
Variable (V), diversity (D) and joining (J) segments.
Which chromosome is the gene for the antibody heavy chain protein?
chromosome 14
How many different options are there for each segment of the heavy chain, variable region of the receptor on the surface of a lymphocyte
48 for V, 27 for D and 6 for J.
What are the segments that make up the variable region of the light chain binding site on the surface of a lymphocyte?
Variable (V), and joining (J)
What bonds hold together an immunoglobulin?
Disulfide bonds
What are the classes of immunoglobulins?
IgM, IgG, IgA, IgE, IgD
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What is the Fc region of an immunoglobulin?
Paired constant region segments. Macrophages have Fc receptors so they can wear antibodies like hats.
What are the subclasses of IgG immunoglobulins?
IgG 1,2,3,4
What are the subclasses of IgA immunoglobulins?
IgA 1,2
What is the main antibody in serum?
IgG
What are the IgG subclasses present in serum in decreasing order of abundance?
IgG1, IgG2, IgG3, IgG4
Where is dimeric IgA found?
Mucosal surfaces; joins to secretory component on basolateral membrane on cells.
What joins two IgA monomers to form an IgA dimer?
A J chain.
What is the first antibody made in an immune response?
Pentameric IgM - has 10 binding sites so has a high avidity, good for agglutination.
What effect does IgE have when it binds to cells?
Histamine is released.
Where does antibody specificity/affinity maturation occur?
In the germinal area of the lymph node.
What is affinity maturation of antibodies?
The antigen of the pathogen is stored in the germinal centre of the lymph node. Then antibodies are tested against it, then new ones are produced and tested so there is a selection allowing for antibodies to be more specific to the antigen produced.
What type of cells leave the germinal centre of the lymph node following the affinity maturation?
Memory cells and plasma cells
What are monoclonal antibodies?
Identical clones of an antibody in which variable regions are produced in mice and constant regions sourced from humans (to prevent inappropriate immune response)
What ending is given to the names of drugs which are chimeric antibodies?
-ximab
What ending is given to the names of drugs which are humanised antibodies?
-xumab
What is haemolytic disease of the newborn?
at least second Rhesus positive baby born to a rhesus negative mother
